It was muddy, it was freezing, it was littered with bear scat. Steve Lewis was hooked.

This was not the first time he'd been underground. Lewis' father, who lacked technical knowhow and carried no equipment more advanced than a sixpack, was the type of old-school cave blunderer who made "spelunking" seem like a dirty word.

But this wasn't his father's kind of spelunking. This was charting the then-unexplored El Capitan Cave -- Alaska's longest, and home of the deepest limestone pit in the U.S. -- on Prince of Wales Island, in Southeast Alaska's Alexander Archipelago, at the random invitation of a friend. This was real caving -- ropes, harnesses, carbide headlamps. And it was brutal: 13 straight hours painstakingly mapping 40 different sections, none longer than three feet, with a compass, fiberglass tape measure and a sketchbook. This was how Lewis wanted to spend the rest of his life.

Indeed, more than 20 years later, Steve Lewis is one of the state's leading cavers and cave defenders, having surveyed and mapped most of the 500-plus known caves throughout the Alaskan Panhandle. (There are likely many more that have not yet been discovered.)

Lewis' earliest brush with subterranean life came as a boy tagging along with his dad on weekend trips throughout the Midwest. In Lewis' early teens, his family spent a year in Micronesia, building a high school on the island of Pruk (now Chuuk) about 650 miles southwest of Guam. There, he stumbled upon and explored a network of tunnels dug by the Japanese during World War II. "It wasn't until many years later that I realized how dangerous this was," he now says, considering the potential for cave-ins or encountering unexploded munitions. "I had no idea what I was doing."

Lewis landed in Alaska in the mid-'80s thanks to a wildlife management master's program in Fairbanks. But halfway through his Ph.D. –– he was studying bat reproduction, a subject that caving had inspired him to pursue –– things began to unravel: "The funding didn't cooperate, the bats didn't cooperate." And then he met Tongass National Forest Sitka District archaeologist Rachel Myron -- where else but in a cave. The two married and built an off-the-grid house in tiny Tenakee Springs on Chichagof Island, the perfect base for caving throughout the Alexander Achipelago. There, he has become a self-taught expert on, and outspoken advocate for, the region's fragile karstlands.

Karstlands -- areas of water-soluble bedrock distinguished by caves, pits, sinkholes and underground drainage -- typically form in limestone. Rain alone will dissolve limestone and carve caves, but acidic runoff from forests and peat bogs, or "muskeg" -- the predominant landscapes of Southeast Alaska and its 17-million-acre Tongass -- speeds up the process. The improved drainage in these areas grows more and bigger trees, making karstlands some of the most attractive timberlands in the Tongass. This is especially true on Prince of Wales Island -- southeast of Chichagof -- which not only boasts Southeast Alaska's largest, best-explored and most accessible cave systems, but also some of its most extensive clear-cuts.

As Lewis and fellow cavers Kevin Allred and Pete Smith explored the region's karst, they couldn't help but notice the destruction wrought by clear-cuts. With no forest canopy to shield it, heavy rain washes soil into the caves, forming silt deposits that can deface -- and sometimes completely cover -- stalagmites, stalactites and other formations. The silt can even plug up entire cave sytems, which sometimes provide drainage and fresh water for local communities. Oils, toxins and organic debris from timber harvesting can also wash into cave systems.

And so, in the mid-'90s, Lewis, Allred and Smith co-founded the Tongass Cave Project, which uses research to help protect Southeast Alaska's karst. Working with geologists, the Tongass Cave Project developed a vulnerability scale, based on factors such as soil depth, abundance of karst features like sinkholes, pits and caves, and contribution to domestic watersheds. In 1997, the U.S. Forest Service used this scale to develop the first federal karstland management program for the Tongass, protecting especially vulnerable pieces of karstland from clear-cutting.

These days, Lewis is working to convince the state of Alaska -- which has no rules to protect karst on private or state land -- to develop a similar program. "There has to be some balance," he says. "There's no reason why we can't develop our resources and still maintain our unique environment."

Lewis' love of the environment goes beyond what lies underground. He also photographs whale flukes as part of a humpback identification project for the University of Alaska Southeast, and monitors sea lion activity on Lowry Island for the Alaska Department of Fish and Game.

"I'm weird," he says. "I'm happier freezing my butt off in the field than wading through paperwork at a nice warm computer."